Automatic stoker and control therefor



June 11, 1935. I w MAYNARD 2,004,533

AUTOMATIC STOKER AND CONTROL THEREFOR Filed March 20, 1933 2 Sheets-Sheet l )4; ATTORNEY! June 11, 1935. w. A. MAYNARD I 2,004,533

4 AUTOMATIC STOKER AND CONTROL THEREFOR Filed March 20, 1933 2 Sheets-Sheet 2 a m use, A 75 2 I H .10

'22 J 74 i/ 51 I I 77 ff K MM 7%; ATTORNEYS 75 INVENTOR. 60 WafAfJLMdl Patented June 11, 1935 umrs I STATES AUTOMATIC STOKER AND CONTROL THEREFOR? a o Walter A. Maynard, Cleveland Heights, Ohio Application March 20, 1933, Serial No. 661,719 3 Claims. (01. 60-52) My invention is an improvement in stokers and relates more particularly to hydraulically operated stokers and an automatic control therefor.

One of the objects of my invention consists in utilizing variations in pressure in the motive fluid to control the cycle of operation automatically under operating conditions, including such conditions which may arise as a result of foreign objects fed into the stoker hopper along with the fuel.

Another object of my invention is to provide full automatic operating control of a stoker mechanism hydraulically, and with minimum power.

A further object is to provide a control of the character described which may befurnished as a unit and independently of the device operated thereby, and which is capable of standardization in manufacture.

A still further object of my invention is to provide an operating control which is simple of construction and inexpensive to manufacture.

Another object of my invention is to construct an automatic stoker of the class described which may be operated and controlled by hydraulic means associated therewith either directly or remotely.

Other objects and advantages of my invention will become more apparent as the following description of several embodiments thereof progresses, reference being made to the accompanying drawings in which like reference characters are employed to designate like parts throughout.

In the drawings:--

Figure l is a longitudinal section-through a Stoker embodying my invention and illustrates the relative positions of the ram and operatingv mechanism just prior to feeding a charge of fuel forwardly of the stoker tube; J

Figure-2 is similar to Figure 1, but shows the ram or plunger extended on its forward stroke;

Figure 3 is similar to Figure 2 and illustrates the relative positions of the parts just prior to the completion of one cycle of operation;

Figure 4 is a diagrammatic view of the hydraulic control;

Figure 5 illustrates a stoker embodying a modification of a part of my invention;

Figure 6 is a longitudinal section through a stoker embodying another modification of the present invention; a 1

Figure '7 illustrates a form of valve forming part of my invention and shows the same in section taken on line '!-l of Figure 11;

"Figure 8 is a section taken on line 88' of Figure7;-- j 7 Figure 9 is a section taken on line 9-43 of Figure '7, and,

Figure lo isa section through a multiple pressure oil pump used in connection with my invention. A Figure ll is a section taken on line H-! l of Figure 7; and,

Figure 12 is an enlarged viewof a portion of Figure 4,illustrating in detail the by-pass valve, metering valveandreliefvalve. v i

In describing my invention as illustrated inxthe accompanying drawings, in which I have'shown several embodiments, I shall refer to' Figures 1 to"4' inclusive which illustrate the preferred formof the invention as applied, in use. In carrying out this form of the invention, the hopper iscarrie'd by 'the'ca'sing or feeding tube 2 and communicates with the-tube through an opening 3. The, tube extends forwardly'and terminates in a tuyere 4. A jacket 5 may be provided ,tosupply airfrom theblower 6 as is indi-v cated'by the arrows, the air vcurrents passing between the jacket and casing, and then through suitable arranged openings =-1 into the tuyere end of the feed tube. The stokerillustrated isof the underfeed type although that myinvention is not'limi-tedto such use.

-Within the tube 2 is a rec'iprocable sleeve 8 which'is provided with'a'n opening '9 in its upper wall for register with the hopper opening 3 to admit a charge of fuelfinto the sleeve "and tube when the parts are in the'po'sition of Figure 1. g A stop I 0 formed integrally withthe casing 2 projects downwardly within the tube and serves to limit the movement of the sleeve 8 in either direction and also limits the forward stroke of the piston or plunger I I operating within the sleeve 8. In further carrying out my invention I have provided hydraulicallyoperated means for operating the piston and sleeve according to a predetermined cycle of operation, wherein the piston ll, andthe'sleev 8 having a charge of fuel delivered therein, are'caus ed to move simultaneously in one direction to advance the charge bodily within the tube 2 although the sleeve and piston are capable of independent movement during any part of the cycle of'operation, such for instance when foreign bodies are present in the fuel charge-which might have 'a tendency to clog the passage'offfuel through the opening 3.

This means-includes the piston H which is slidable in the sleeve' 8 and which is connected by a rod [2 to a head l3 operating in the cylinder l4 it is 'to'be understood I carried by an end of the sleeve 8. Suitable ports [5, I6, I! and I8 communicate withthe interior of the cylinder and are arranged to admit and exhaust oil or other fluid under pressure from the cylinder. The right hand end of the cylinder l4 in the figures isformed with a head l9 which operates within the chamber 20. The chamber 20 is, of course, equipped with suitable ports 2|, 22, 23 and 24 for the admission and exhaust of the operating fluid under pressure.

Before proceeding further with the description of the fluid operating means and automatic control thereof, I will briefly describe the modified forms of stoker constructionwhich, are particularly adapted to and form part of my invention.

These are illustrated in Figures 5 and 6 and are somewhat similar to the form shown in'Figures lto3. v

The form shown in Figure 5, however, is provided with a reciprocatory sleeve formed'either integral with or attached to the piston! [to move therewith in either direction. "The sleeve is open at 25 to permit the full charge to be delivered thereto when the same registers with the opening 3. A connectingrod 12E connects the piston H with a head 26 operating in a cylinder 21. Suitable po'rt's'28 and'25 are provided for admitting fluid underpressure to ,either side of the head 26, while the stmketr the piston H. may be predetermined by a pin placed in any-one'of the series of openings-30'. A stop sl limits the stroke of the piston I I'm onedirection.

In Figure 6 the constructionis very similar. to that shown in Figure 5, but} it will'be'noted that I have eliminated the sleevea in its entirety. Proceeding now with the description of the operating and control means, reference is madefirst to Figure 4 in whichthe general organization is illustrated in diagrammatic form. electric motor 32 is connectedto drivetheloil pump 33, there beingconnections from the pump to .an expansion chamber ,34 to cushion any sudden changes in pressure in the lines A supply pipe35 leads fromthe expansion chamber to the control valve 36 at 58. v H

A return conduit? 31 connects the control valve 36 at.3la as shown imljigurge 9 withitheoil pump 33 while a conduit 38; leads from the conduit 35 through a pressure relief valve, a by-passvalve 49 and 'a metering valve M to a valve position motor 42, the'oil or otherfluid passing through these conduits under pressure being admitted to the 'motor 42 to operate the same; Inthis con--. nection the metering valve,: of any well known construction serves to regulate the volume of fluid under pressure passing to the motor 42. .A return pipe 43 returns some of the oil-from the valve motor to the line 44 which has connection'with the bypassvalve.40 and anoil reservoir 45. In this way the oiLafter having passed through the valve motor is returned {to the oil reservoir through the conduit 44 and may be 'passed through the pump. again. I J

r In Figures '7 and 8 I have illustrated in detail the control valve 35 and the driving motor 42.

' The motor 42 consists primarily of a casing 45 which houses a gear type of pump comprising the gears 41 and 48, the oil inlet. being indicated at 49 and the outlet atv 50 (Figure 4) The motor is preferably mounted on the valvecasing and has a direct drivingconnection through a'shaft 5! with the rotary valve member 52. V The end 51a of the shaft'is flattenedto fittheslot 5) for a directfdriving connection-with the rotary plug 52, [The'valve casing-36 isprovided with a' series 'of 'ports 53, 54 and 55 extending radially through the casing and adapted to register with a groove 55 formed lengthwise in the outer surface of the rotary member and communicating with an annular groove 51.

A port 58 formed in the valve casing always communicates with the-groove 51. The plug or rotary member 52 is provided with a relief pressure opening 59o communicating the pressure side of the motor with the under side of the plug 52, and is also provided with an axial bore 59 extending throughout the length of the plug which will relieve pressures which might be built up under. the plug. A zenith plug 60 communicates with the bore 59 to relieve pressures into the upper chamber 63. The zenith plug 60 is provided as a convenient means of controlling the relief 'of pressure through the bore 59, since this'plug is provided with a restricted orifice as P shownin Figure '7. The plug 60 is threaded for installation in a tapped hole in the plug 52 and may be interchanged withother plugs having larger or smaller orifices,if desirable, to adjust the operation of the valve. If the, orifice in the plug 60 weretoo large, it would releasetoo much fluid from the pressure side of the motor through 5911 and consequently the motor would not receive suflicient pressure to turn the-plug 52 to the next position in its cycle of operation. It will be noted that the plug 52 is tapered slightly downwardly and that pressure is exerted on the plug by means of a spring 5! to maintain it in seating relation with the. inner walls of the casing. A groove 62 is also formed in the plug to register with any one or moreof the ports 53,54 or 55, depending on the position of the plug to deliver the oil tothevupper chamber 63 formed in the valve casing. I have shown in Figure 7 the ports 53, 54 and'55 arranged or spaced at 120. intervals, this figure being a section taken on line of Figure 11. v

In' order to exert a downward pressure on the plug 52, the spring BI is preferably enclosed within theupwardly extending stem 54 formed on the plug, the upper extremity of the coil spring abutting the cap: which is removably secured to the valve casing 36. It is desired that the stem 64extend upwardly to a point just out of contact with the cap to permit passage of oil from the lower part of the valve through the plug 60 and up into the chamber 53 over the top of the stem 64. Openings 65 are cut in the casing (Fig. 9) to permit overflow of oil from the chamber 63. l

The valve stem 64 is formed as a cam of two or more sides in cross section (Figure 9), and operates between flat resilient members 6'! and 68, the latter beingbowed slightly intermediate its ends as illustrated. In this manner the plug when rotated throughout its cycle of operation will properly align its ports or grooves with the respective ports in the casing 35 during each successive step in the cycle. The springs 61 and 68 are supported in and extend across the casing as illustrated, the ends of the springs resting in the slots 66. Longitudinal displacement of the spring members 61 and 68 is prevented by the flange of the cap 65.

In Figure 10, the oil pump is shown in cross section and is of the usual gear type in which the driven shaft I0 connected with the" electric motor 32, drives the pump gears TI and i2 keyed to said shaft. Pump gears 13 and 14 are keyed to the idler shaft 15, the respective gears H and I3 and gears 12 and 14 being of corresponding sizes and operating in separate pump compartments l6. and T! to pump the oil through the respective outlets l8 and 19 at different volumes whenthe shaft 10 is rotated. 1

I will now describe the operation of the inven-- tion as particularly applied to Figures 1 to 4 inclusive.

Assuming that the control valve is connected to be operated as illustrated in the diagrammatic showing in Figure 4 and that the valve is connected to operate the embodiment shown in Figures 1 to 3 inclusive, the operation may be de-' scribed as follows:

To begin the cycle of operation with the valve parts in the position shown in Figure 7 and the control units connected to the stoker as shown, the electric motor 32 is started and drives the pump 33 to force oil under pressure-to the valve motor and the control valve 36. The volume of oil delivered by the pump is selective by means of the cooks 80 and 8t, since either one of these may be closed if desired. Any suitable driveconnection may be provided between the motor and pump and likewise a different type of pump may be used, if desired. Where operating conditions call for relatively uniform fuel feed-at all times the simple type of gear pump is employed. Where variations from uniform feed are desirable, a compound gear pump or a type of adjustable or variable displacement pump may be used.

Since the volume output of the oil pump is relatively large as compared with the capacity of the valve position motor 46, it is desirable that some means be provided to slow down the speed of the valve motor. The oil line between the check valve and the valve motor is relatively small in diameter as compared with the line between the pressure relief valve and the by-pass valve. The by-pass valve is set so that it will open under relatively low pressure and allow the oil passed through the pressure relief valve to be returned to the intake of the oil pump or the oil reservoir, but at the same time maintains a moderate pressure and a constant supply of oil in the line to the valve position motor. This is sufficient to'operate the valve position motor at moderate speed until the control valve is in the next position and the pressure in the oil pressure line is reduced.

Oil under pressure is delivered to the valve motor as already described. Oil under pressure is also delivered through the conduit 35 to the control valve 36 where it enters the valve through the port 58 and is communicated by means of the annular groove 51 and the groove 56 (Figure 7) to the outletorport 55. This oil under pressure is thus communicated to one sidevof the piston head H3 in the chamber as indicated more clearly in Figure 1. As the oil enters the chamber 20 under pressure it forces the head 19 and the cylinder l4 and the sleeve 8 to the left as indicated in Figure 2. This-closes the opening 3 between the hopper and the interior of the tube and during the movement of. the sleeve to the left the piston H is also thrust to the left with the sleeve until a Wall of the sleeve and the piston abut the stop Ill extending into the sleeve 8. In this manner the charge of fuel is advanced in the sleeve and is ultimately delivered into the tuyre and into the fire pot of the furnace.

It will be noted that during this step in the operation of the invention the pressure is relieved on the opposite face of the head l9 through the port 23 which is connected with the control valve through the port 53 having communication with a groove 62. similar to the groove 62 formed in the plug 52, to permit any oil which may remain in this part of the circuit. to. be discharged through the plug and out through the chamber 63 and theopenings 66; The first part of the cycle of operation is thus complete.

The next step is illustrated in Figures 2 and 3 and represents the action occasioned by the ro-' tation of :the plug 52; by yirtu'e of the actuation of the valve motor 42 to rotate the plug to a po sition where the grooves 56 :and 51 are in communication with the port 53. The valve plug is rotatedv to the position as a; result ofpressure building up in the valve motor lineafter the piston H and sleeve 3 have reached their extreme limit of movement 'to the left in Figures 1 and 2. When the operation of this or any other part of thecycle is completed or the stoker is clogged, the movement of the operating piston is slowed down or stopped. The continued operation of the pump 33will thus increase or'build up the pressure in supply line 35. Pressure relief valve 39 is set to remain'closed until the pressure III rises to a predetermined degree, then it willopen to communicate the fluid under pressure through the by pass 4B'and metering valve 4| to the motor 42 which when actuateddrives'the .valve plug 52 to the next consecutive position.

The valve is now in position todeliver oil under pressure as indicated-in Figure 2 through the conduit 23 to the opposite face of the head 19, the pressure on the oil in the chamber 20 being relieved through the port 24 asthehead I3 moves to the right by the admission of oil under pressure into the left handend' of the chamber 20 in Figure 2, the sleeve 8 is withdrawn to a position indicated in Figure 3 because ofthe fact that this oil under pressure is also admitted through the ports I! and I 8 to the interior of the cylinder M, the piston His maintained in its extreme left hand position until the head Iii reaches the right hand end of the chamber 2!]. Of course, the oil in the cylinder Mand on the left hand face of the head 13, Figure 2', is released through the port l6, during the movement of the head 19 to the right. .L

During this part of the operation .it 'will be seen that the piston'l 1 causes the charge of fuel [6 to the left hand face of the piston l3 as indicated by the arrows in Figure 3. At the same time pressure is relieved through the conduit 23 and from the opposite face of the piston I3 through the ports I! and I8 and the pistons H and I3 and the connecting rod H are then caused to travel to the'right in Figure 3 toagain assume the position of the parts in Figure 1 and to complete the cycle of operation of the invention. As the piston is returnedto its extreme right hand limit of motion, it again uncovers the opening 3 between the hopper and the interior sliding sleeve 8 and permits the'next charge of fuel to enter the sleeve. This cycle ofoperation is repeated automatically and in the manner described and fuel is thereby fed from the hopper and along the stoker tube and is discharged into the fire pot of the furnace. .'The. cycle control valve is soarranged that it not only distributes the oil under pressure tothe propercylinders'in order throughout the cycle but also releasestheoil from the other partsof the system where it is not to be under: pressure and allows it tobe returned tothe inlet of the oil pump. or to the oil reservoir. It-is to be understood that the cycleccontrol ,valve operates in a sort of step by step'manner andgis not in continuous motion. The .valve position motor is op-' erated automaticallyby the changes in pressure in the oil pressurelines asl the cycle progresses sothat it will turn the cycle control valvet'o the next desired outlet and leave'it there until that partof thev cycle; of operation is complete and willthen turn it automatically to the next port so that the-cycle will be continued'as long as the electric motor is running. I

The valve position motor is an oil'gear motor so arranged for driving the control -.valve that when oil is supplied to the motor .under pressure itwill revolve to turn thecontrol valve to the desiredposition. For example; when oil-under pressure is being delivered through the conduit 24,:the pressure-in the oil pressure lines will be proportional to the pressure required to move the sleeve, 8, and piston ll through the first stroke of the cycle of operation. When the end of that stroke is reached, the sleeveBor the piston H is stopped ,bythe stop Ill, and, as-the oil pump continues tov operate there is an immediate or relatively large vaincrease of pressure in the oil pressure line. The pressure relief valve 39 may be set so that it will close ofi the line and will not open torelieve that pressure'for any ordinary operatingpressures that will occur during any part of the cyclewhen the sleeve or, piston are moving. Whenthe oil pressure is thus increased materially above such normal operating pressure, the pressure relief valve will open and release the oil under pressure to the-valve position motor and through the by-passvalve to the inlet of the oil pump andthe oil reservoir. The valve position -motor then 'revolvesand turns the cycle control valve top-its .next operating position. This releases the oil in theoil pressure lines so that the pressure in, that line is materially re-.- duced, the valve position motor stops rotating and leaves .the cycle control valve inthe proper position for the next-step in the cycle of operation. This; is continued automatically as long as the electric motor operates the oil pump.

When it is'desired to;.flllthe sleeve .8 and the stoker tube with fuel prior to the actual operation of the stokergthis, may be accomplished by first-filling the hopper l with fuel and then closing the conduit 24 when 'thexpiston andsleeve are in the position shownzin Figure 1. In this manner the sleeve 8- will remain stationary and the piston I l will-act alone-as a ram to force the fuel through the'tube 8 and the tuyere. 1

It will be seen that by my invention I have constructed a simple control mechanism which; is particularly well adapted for the automatic control of stokers and which can be manufactured inexpensively because ofsuch simplicity and the possibility of standardization of parts The apparatus is so designed that it maybe built in units and the stokerjmay' be operated through the control means'which may be, if -desired,located in some remote place, It will also be seen that by my invention a: wide range of operating conditions may be provided for with little or no change in the actual-construction or. arrangementof the parts. It is to be understood that while I have shown :thecontrol in connection: withthe automatioioperation of astoker, this part ofimy invention can be suitably employed to control other'apparatus if desired,

I It .will be observedv that by the present invention ample power may be delivered 'to the stoker for-theefficient feeding offuel through the stokerand thatinthe event foreign objects are inadvertently fed through the hopper with the fuel and are of such-size as might. tend tov clog the opening or unduly oppose the operation of the-sleeve .8 and the piston llythe piston. may

I be operated independently of the sleeve to loosen up such clogged condition, .and'when the oil pressure operating the piston-is materially increased above normahoperating pressures, due to abnormal operating conditions such as clogging, the pressure relief valve will open and release the oilunder pressure to'the valve position motor and through :the by-pass valve 40 to the inlet of the oil pump orthefloil reservoir.

Various changes in the details of construction and arrangement of parts may be made without departing "from the spirit-of my invention'or the scope of the appended claims.

;,I,claim:

1. In a,.hydraulic control system including a source of fluid under-pressure and a plurality of reciprocable members operated by said fluid under pressure, a distributing valve comprising a casing having a plurality of 'outlets communicating with said members-a rotatable plug within the casing having an opening" in constant communication with said fluid sourceand'progressively with said outlets as the plug is rotated; said plug having a discharge opening for simultaneous communication with another of said outlets to relieve pres" sure on one side of one of said reciprocable members while fluid under pressure is delivered to said one member in an opposite direction, and hydraulically operated means for rotating said valve,said last named means being responsive to Variations in pressure on the fluid in said system.

2.. In a 'hydraulic'control system including a source of fluid under pressure and a plurality of reciprocable members operated by said fluid under pressure, a distributing valve comprising a casing having a plurality of outlets communicating with said members, a rotatable tapered plug fitting within the casing and having an opening in constant communication-with said fluid source and progressively with said outlets as the plug is rotated, said plug having a discharge opening for simultaneous communication with another of said outlets to relieve pres'sure on one side of one of said reciprocable members while fluid under pressure is 'delivere'dto' said one member in an opposite directiom'saidplug having a stem projecting axially therefrom, a'spring within said stem to normally tend to thrust the plug inwardly of the casing, and means carried by the casing and engageable with the stem to align the respectivecommunicating openings in the plug and easing as the plugis advanced throughout its succession of rotated positions.

3..I n a hydrauliclcontrol system including a source of fluid under pressure and a plurality of reciprocable. members operated by said fluid under pressure, a distributing valve comprising a casing having a'plurality of outlets communicating with said members, a, rotatable tapered plug fitting within the casing and having an opening in constant communication with said fluid source and progressively with said outlets as the plug is rotated-said plug having a discharge opening for simultaneous communication with another of said communicating openings in the plug and casing as the plug is advanced throughout its succession of rotated positions, said last named means comprising a pair of resilient strips extending across the casing on opposite sides of said stem, said stem having at least two flat sides for engagement with said strips.

WALTER A. MAYNARD. 

